CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss, Net of Deferred Taxes [Member]	Unallocated Common Stock of ESOP [Member]	Unearned Restricted Stock Award Common Stock [Member]	Common Stock Held by BMP [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2011	$ 516	$ 231,521	$ 358,079	$ (9,709)	$ (3,239)	$ (3,037)	$ (8,655)	$ (204,442)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income recognized during the period, net of tax				69					69
Shares issued in exercise of options (16,960 shares, 833,334 shares and 455,051 shares during the years ended December 31, 2014, 2013, and 2012, respectively)	4	5,604
Excess Tax benefit of stock benefit plans		389
Amortization of excess fair value over cost - ESOP stock and stock options expense		1,168
Release from treasury stock for equity plans, net of return of shares to treasury for forfeited shares		359				(1,927)	(145)	1,858
Net income for the period			40,308						40,308
Cash dividends declared and paid			(19,221)
Amortization of earned portion of ESOP stock					232
Amortization of earned portion of restricted stock awards						1,842
Balance at Dec. 31, 2012	520	239,041	379,166	(9,640)	(3,007)	(3,122)	(8,800)	(202,584)	391,574
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income recognized during the period, net of tax				4,881					4,881
Shares issued in exercise of options (16,960 shares, 833,334 shares and 455,051 shares during the years ended December 31, 2014, 2013, and 2012, respectively)	8	11,220
Excess Tax benefit of stock benefit plans		292
Amortization of excess fair value over cost - ESOP stock and stock options expense		1,176
Release from treasury stock for equity plans, net of return of shares to treasury for forfeited shares		524				(2,082)	(213)	2,064
Net income for the period			43,548						43,548
Cash dividends declared and paid			(19,728)
Amortization of earned portion of ESOP stock					231
Amortization of earned portion of restricted stock awards						2,011
Balance at Dec. 31, 2013	528	252,253	402,986	(4,759)	(2,776)	(3,193)	(9,013)	(200,520)	435,506
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income recognized during the period, net of tax				(3,788)					(3,788)
Shares issued in exercise of options (16,960 shares, 833,334 shares and 455,051 shares during the years ended December 31, 2014, 2013, and 2012, respectively)	1	277
Excess Tax benefit of stock benefit plans		71
Amortization of excess fair value over cost - ESOP stock and stock options expense		1,111
Release from treasury stock for equity plans, net of return of shares to treasury for forfeited shares		646				(1,849)	(151)	1,554
Net income for the period			44,246						44,246
Cash dividends declared and paid			(20,106)
Amortization of earned portion of ESOP stock					231
Amortization of earned portion of restricted stock awards						1,976
Balance at Dec. 31, 2014	$ 529	$ 254,358	$ 427,126	$ (8,547)	$ (2,545)	$ (3,066)	$ (9,164)	$ (198,966)	$ 459,725